Cell Type-Dependent Induction of DNA Damage by 1800 MHz Radiofrequency Electromagnetic Fields Does Not Result in Significant Cellular Dysfunctions

Background: Although IARC clarifies radiofrequency electromagnetic fields (RF-EMF) as possible human carcinogen, the debate on its health impact continues due to the inconsistent results. Genotoxic effect has been considered as a golden standard to determine if an environmental factor is a carcinogen, but the currently available data for RF-EMF remain controversial. As an environmental stimulus, the effect of RF-EMF on cellular DNA may be subtle. Therefore, more sensitive method and systematic research strategy are warranted to evaluate its genotoxicity. Objectives: To determine whether RF-EMF does induce DNA damage and if the effect is cell-type dependent by adopting a more sensitive method gamma H2AX foci formation; and to investigate the biological consequences if RF-EMF does increase gamma H2AX foci formation. Methods: Six different types of cells were intermittently exposed to GSM 1800 MHz RF-EMF at a specific absorption rate of 3.0 W/kg for 1 h or 24 h, then subjected to immunostaining with anti-gamma H2AX antibody. The biological consequences in gamma H2AX-elevated cell type were further explored with comet and TUNEL assays, flow cytometry, and cell growth assay. Results: Exposure to RF-EMF for 24 h significantly induced gamma H2AX foci formation in Chinese hamster lung cells and Human skin fibroblasts (HSFs), but not the other cells. However, RF-EMF-elevated gamma H2AX foci formation in HSF cells did not result in detectable DNA fragmentation, sustainable cell cycle arrest, cell proliferation or viability change. RF-EMF exposure slightly but not significantly increased the cellular ROS level. Conclusions: RF-EMF induces DNA damage in a cell type-dependent manner, but the elevated gamma H2AX foci formation in HSF cells does not result in significant cellular dysfunctions.